|同行评审的重要价值一直被学术界广泛认可，然而其过程的不透明广受诟病。近年来，区块链技术的快速发展正在迅速推动以太坊等开放式智能合约平台的成熟，为开发去中心化的评审系统奠定了坚实基础。然而，目前去中心化的评审协议面临两个有挑战性的问题。首先，由于区块链记录的信息是透明公开的，若评审方的身份在评审结果产生前被公开，会导致匿名性难以保障，不利于维护评审过程的公平性。其次，由于智能合约中函数的每一次调用都要花费一定量链上资源，执行包含n位评审方的协议需花费O （n）链上资源，导致可扩展性难以保障，协议难以应用到实际场景。本文提出一种基于区块链的轻量级匿名审稿协议（Blockchain-based Lightweight Anonymous Review，BLAR），旨在解决去中心化评审协议的匿名性和可扩展性两个关键问题。BLAR协议不需要在评审结果展示前在区块链上存储任意可能导致指派信息泄露的信息，包括但不限于被选中评审方的账户地址或其哈希值，从而使攻击者无法确定性地找出对应某投稿的评审方。同时，BLAR协议不依赖区块链进行存储与计算，而是仅利用区块链进行验证和可信性保证，从而在最小程度造成区块链链上负担的情况下，保证数据汇聚与处理的可信性。我们证明，只要主办方和评审方存在至少一位诚实参与者，BLAR协议一定能执行完毕，且一定能产生符合评审者打分的正确结果。我们还证明，当全部协议参与方具备理性时，执行BLAR协议全过程的成本为O （1），独立于参与方数量的规模。我们在以太坊官方测试网络上实现了BLAR协议，并进行了实验评估。结果表明，无论协议参与方的规模大小，BLAR协议都可以将匿名评审的执行成本降低到1美元以下，远低于现有工作中方案的执行成本，具备了实用性。
|关键词: 区块链 智能合约 匿名评审系统 可扩展性 活性
|Blockchain-based Lightweight Anonymous Review System
LI Chao1,2, WANG Jian1,2, LIU Jiqiang1,2
|(1.Beijing Key Laboratory of Security and Privacy in Intelligent Transportation, Beijing Jiaotong University, Beijing 100044, China;2.School of Computer and Information Technology, Beijing Jiaotong University, Beijing 100044, China)
|The important value of peer review has been widely recognized by the academic community, but the process of peer review has all along been criticized to be lacking transparency. In recent years, the rapid development of blockchain technology is quickly promoting the maturity of open smart contract platforms such as Ethereum, laying a solid foundation for the development of decentralized review systems. However, decentralized review protocols currently face two challenging problems. First, since the information recorded by the blockchain is transparent and open, the identities of the reviewers are disclosed before the review results are produced, which makes anonymity difficult to be guaranteed and is not conducive to maintaining the fairness of the review process. Second, because each invocation of a function in a smart contract costs a certain amount of money, a protocol involving n reviewers could result in O(n) monetary cost, it is thus difficult to guarantee scalability and to apply such a protocol to real scenarios. In this paper, we propose a blockchain-based lightweight anonymous review protocol (BLAR) to solve the two key problems, anonymity and scalability, faced by decentralized review protocols. The BLAR protocol does not need to store any information that may lead to disclosure of assignment information on the blockchain prior to announce of review results, including but not limited to the account address or hash value of the selected reviewers, thus making it impossible for an attacker to identify the reviewers assigned for a manuscript. Also, BLAR protocol does not rely on blockchain for storage and calculation, but only uses blockchain for verification and credibility guarantee, so as to ensure the credibility of data aggregation and processing with the minimum burden on the blockchain chain. We demonstrate that as long as there is at least one honest participant between the host and reviewers, the BLAR protocol cannot be aborted, and the results are guaranteed to be correct. We also show that when all parties are rational, the cost of implementing the entire BLAR protocol could be reduced to only O(1), regardless of the scale of participants. We implemented and experimentally evaluated the BLAR protocol on the official Ethereum test network. Our results demonstrate that BLAR protocol can reduce the cost to less than $1 regardless of the scale of the participants, indicating that BLAR protocol is a practical solution with its cost much lower than the implementation cost of existing solutions.
|Key words: blockchain smart contract anonymous review system scalability liveness